Quite a long while ago, NT was heralded as Microsoft's multi-platform OS, and it ran on Intel, MIPS and PowerPCs. David Cutler (one of the original VMS architects) designed it to be both portable and backwards-compatible (to a certain extent), and it was a combination of platform politics and Intel's market dominance that caused the non-Intel variants to vanish outside Microsoft's labs.
The ironic bit is that if it proves to be true (all of it), then Microsoft is using its only portable technology to break compatibility between game console generations.
It looks like HD-DVD players will have to support H.264, MPEG-2 and... Windows Media Player 9. Which, for a change, is a good thing. The VC-9 codec is pretty good, and its acceptance as a standard at this level requires both a "feature freeze" and a certain degree of openness.
Of course it will boost sales of editing and content management tools for the Windows platform, but hey, this time the playing ground is supposedly a level one - at least until DRM comes into the picture.